In practice, in dependence an objective, mathematical models of different complexity are applied. So in programs of the training type the models describing only key parameters are used. Such as:
Technical progress made possible design of the big functional blocks containing in one scheme of one thousand interconnected transistors. Development of such schemes became impossible at experimental debugging on the model.
If nonlinear models of components are entered into the equations describing the scheme, it becomes rather difficult to solve these equations. Thus in programs of expense of machine time for definition of the nonlinear functions describing various semiconductor devices make considerable part of the general expenses of time.
The program written on the specified algorithm confirmed justice of these algorithms and relative accuracy of the mathematical description of bipolar transistors. Results of the received program were compared to professional CAD programs for the same transistors and identical corresponding parameters. Changing input parameters will perhaps rather close come nearer to their results a little.
At the description of difficult devices and multidimensional systems their output characteristics on the basis of which macromodels are created are used. The models defining electric properties are used for the exact analysis.